The present invention relates to the growth of cells under sterile conditions, especially explant cultures of plants. More particularly, the present invention relates to (i) novel and improved containers for containing and nurturing explant cultures; (ii) methods of growing plants in explant culture employing the aforesaid containers; (iii) molds for manufacturing the aforesaid containers; (iv) methods of manufacturing the aforesaid containers using the molds; and to (v) apparatuses employing the molds for manufacturing the aforesaid containers.
The present invention is intended to facilitate large scale propagation of plants commonly grown in cell culture and further to allow their distribution from a central facility to planting areas remote from the facility. Plants suited to use with the proposed invention include, but are not limited to, bananas, cassavas, strawberries, potatoes, beets, onions, and orchids and other ornamental flowers and food crops. Similarly, the present invention may find used in cultures of animal cells or in culture of embryos from pluripotent animal cell lines.
The present invention is designed to allow efficient low cost production of uniform plants, and to facilitate such production by unskilled personnel in facilities with a minimum of equipment. Further, the present invention is designed to facilitate transfer of plants grown in explant culture to the soil while minimizing root damage and other types of trauma to the plant.
The prior art teaches a number of devices for plant germination and propagation.
One prior art device, disclosed in U.S. Pat. No. 1,279,310 is designed only for assaying viability of seed samples, and not for facilitating their further cultivation.
Similarly, U.S. Pat. Nos. 2,571,491; 2,323,746; 5,27,951 and 526,512 teach a number of methods for planting seeds between sheets or strips of porous material. These patents all deal with devices and methods for predetermining the spacing and orientation of seeds prior to planting in a field. U.S. Pat. No. 4,910,911 teaches a similar device designed to contain young plants instead of seeds. While reference is made in these patents to inclusion of nutrients or fertilizers, application of such materials is continuous throughout the growing period from the time of planting until the material is depleted. If changes in concentration of specific components of a nutrient or fertilizer occur, they are reduction over time. Delayed delivery of a nutrient mixture therefore requires application to the growing plants from a source outside the patented device. All of these inventions are also designed to disintegrate over time, releasing seeds or plants contained therein into the soil. Most relevant to the present invention, none of these prior art patents insure sterility of seeds or plants during early stages of growth.
Additional prior art devices for propagating and growing plants are disclosed in U.S. Pat. Nos. 3,172,234 and 5,081,791. These devices are not dissolvable in soil, but require either inclusion of all required nutrients in a rooting medium, or addition of nutrients from an outside source. As with aforesaid prior art devices, no provision for sterile cultivation is made in these devices.
All of the aforesaid prior art devices are designed for use with seeds or young plants, not for use with cells from explant culture.
An additional prior art device is disclosed in U.S. Pat. No. 4,000,580. This device makes no provision for sterility during growth and is designed for small-scale experiments employing seeds, not for commercial scale propagation of explant cultures.
Additional prior art devices exist for use in plant culture facilities. One such device is disclosed in U.S. Pat. No. 5,335,345. This device is designed specifically for transferring plants grown in culture from one container to another. U.S. Pat. No. 5,212,906 teaches a device for growth of plants under sterile conditions. This device is specifically designed for use with plant bodies and requires the use of external nutrient supplies and gas supplies. An additional prior art device is disclosed in U.S. Pat. No. 5,525,505. This device can be used to incubate plant material in individual plastic chambers, which are then placed in tray of liquid nutrient broth. This arrangement requires special provisions for keeping the nutrient broth, which is external to the growth chamber, free of contaminants.
There is thus a widely recognized need for, and it would be extremely advantageous to have, a container for propagating cell culture material under sterile conditions which facilitates addition or change of culture medium, or specific components thereof, from a source within the container, but separate from the incubation chamber.